What are Piggyback IOL ?

A piggyback intraocular lens (IOL) refers to the implantation of a second intraocular lens in an eye that already contains a posterior chamber IOL (PCIOL). This approach is used to correct residual refractive errors after cataract surgery or refractive lens exchange when corneal laser enhancement is not suitable.

Instead of replacing the existing lens, a second IOL is placed in the ciliary sulcus — effectively “piggybacking” on the original IOL. The technique offers a reversible, adjustable, and less invasive alternative to IOL exchange.

Indications

Piggyback IOL implantation is indicated in the following situations:

Residual refractive error (myopia, hyperopia, or astigmatism) after cataract surgery High ametropia not correctable with a single IOL Post-keratorefractive eyes (LASIK, PRK) with unpredictable IOL power calculations Multifocal or EDOF vision enhancement when the initial implant was monofocal Anisometropia or postoperative refractive surprises

(Source: EyeWiki – Secondary Piggyback IOLs)

Types of Piggyback IOL

True Piggyback IOL: Both lenses placed “in-the-bag.” This is largely avoided today due to risk of interlenticular opacification. Sulcus-based Add-on IOL: The preferred modern method. The supplementary lens is designed for ciliary sulcus placement, with a posterior concave surface and rounded edges to prevent iris chafing.

(Source: Springer Ophthalmology 2024)

Pre-operative Assessment

Before surgery, careful evaluation includes:

Manifest refraction and stability of residual error Anterior chamber depth (ACD) and sulcus space Endothelial cell count Primary IOL stability and position Absence of posterior capsule rupture or uveitis

(Source: PMC – Piggyback IOL for Residual Refractive Error)

Advantages of Piggyback IOL

Avoids risks associated with explanting the original IOL Reversible and modifiable Shorter surgical time High patient satisfaction Minimal induced astigmatism

Potential Complications

Although generally safe, possible complications include:

Interlenticular opacification (ILO) Pigment dispersion or iris chafing (if lens not sulcus-specific) Glare or halos Increased intraocular pressure IOL decentration

Using specially designed sulcus-based IOLs greatly reduces these risks.

Outcomes

Multiple studies have demonstrated excellent refractive accuracy and visual improvement following secondary IOL implantation. Modern add-on IOLs, such as the Rayner Sulcoflex and Medicontur AddOn, are well-tolerated, maintain stability, and provide high patient satisfaction.

(Source: Dovepress Ophthalmology Reports)

Conclusion

Piggyback IOL implantation is a safe and effective option for correcting residual refractive error in pseudophakic patients. It preserves the integrity of the primary IOL and allows precise visual optimization when laser enhancement is unsuitable. The technique requires proper lens selection, careful spacing, and meticulous postoperative follow-up to ensure long-term clarity and stability.